The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Internal combustions engines combust an air and fuel (A/F) mixture within cylinders to produce drive torque. More specifically, the combustion events reciprocally drive pistons that drive a crankshaft to provide torque output from the engine. The fuel is delivered to the engine by a fuel system. The fuel systems of some vehicles include a plurality of fuel tanks. For example, some fuel systems include a primary fuel tank and a secondary fuel tank, wherein each fuel tank includes its own filler neck.
The fuel levels within the fuel tanks are monitored and the vehicle operator is informed as to the amount of fuel remaining in each tank. More specifically, a fuel level sensor is provided in each tank. Each fuel level sensor is responsive to the fuel level in the tank and generates a signal based thereon. The amount of remaining fuel is determined based on the signals.
Traditional fuel level monitoring control includes rationality diagnostics to determine whether the fuel level sensors are functioning properly. However, the traditional fuel level monitoring control rationality diagnostics are unable to discern between a fuel level signal that is stuck at empty and a fuel tank that has not had any fuel added. In most fuel system designs this is not an issue, because the fuel tank will be refueled on a regular basis.
In a dual fuel tank system having separate fueling necks, however, the vehicle operator often decides not to add fuel to the secondary fuel tank for an unspecified amount of time. That is to say that the traditional fuel level monitoring control can not diagnose whether a fuel level is stuck at empty versus resting at empty because no fuel has been added to the secondary fuel tank.